Stellar magnitudes and distances (parallax)
The solar system and stars · Physics
Solar system
Interactive 3DAll eight planets in orbit around the Sun, with Saturn's rings and Earth's Moon.
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Study notes
Earth orbits the Sun at ~1.5×10¹¹ m with a period of 1 year. Kepler's third law (T² ∝ r³) predicts Mars's period: Mars is 1.52 AU out, so T = √(1.52³) ≈ 1.88 Earth years — matching the observed 687 days. Neptune, at 30 AU, takes √(30³) ≈ 165 years per orbit.